The market for metal containers has developed due in part to the introduction of the easy open end. While the easy opening feature has been shown to be both effective and convenient, it has given rise to a collateral problem of littering, since traditionally the easy opening tab was pulled free from the container to expose the contents and then subsequently discarded. The indiscriminate disposal of the pull tabs is not only unsightly, but can also present a safety hazard particularly on beaches and in parks. Further, the relatively small size of the separated tab on beverage containers presents a challenge to those concerned with the collection and recycling of waste material. The solution to this problem resides in a nondetachable tab and preferably a tab which is of compatible material with the end closure and is therefore recyclable.
While the industry has addressed this problem by developing a number of closure structures, one of the more successful has been a can end which employs a retained ring-pull tab. In this structure, the tab is joined to the container end by a rivet which carried upon a scored displaceable panel in the end panel that serves as the pour opening of the container end. Typically, the ring-pull of the tab has an aperture to receive a rivet that is an integral part of the center panel of the end closure. Since the tab functions to permit the breaking and tearing of the scored portion of the end panel about the rivet it must be sufficiently rigid to prevent distortion of the area about its aperture when pulling force is applied to the lift end of the tab to effect rupture and displacement of the scored portion.
For many years full panel easy open end structures were made to permit the removal of substantially all of the central portions of an end panel closure. These arrangements included a ring pull tab with a tab nose and a tab lift connected by a central web usual apertured to receive the integral rivet for the end panel rupture and then lifting. The ring pull or tab lift would fracture the score in the area adjacent the tab nose end pulling the ring pull or tab lift would tear the scored panel and remove or displace same from the end. Such an approach was fine except that the portion removed was not retained and would not overcome the litter problem. Similarly, retained tabs or ring-pull tabs provided with small openings, for beverage containers in particular, and the ring-pull have an integral rivet arranged so that the break would occur thereabout as the displaceable panel defined by a score was removed from the can. The combination of a pour opening concept based upon the full panel concept and the retained tab concept has not been used. More particularly, to some extent retained tabs of the type just described are similar to full panel opening ends in that the ring-pull is first lifted to rupture or break the scored portion near the periphery and then the ring-pull is yanked radially across the end to open while tearing along the score and folding back the tab but the foldback is uncertain. The scored displaceable panel is unconventional in that it defines a small pour opening and not a removable full panel. In fact, there remains a hinge portion which is unscored to retain the pulled displaceable panel and the terminations of the score about the hinge portion are curved away from each other to discourage further tearing.
A problem however arises when packaging noncarbonated beverages with such closures; that is to say that, the internal support for the end closure is not provided by the pressure of the product packed within the container. Therefore, the loads imposed when filling and after packing must be withstood entirely by the construction and design of the end. Approaches which have been tried using the retained ring-pull approach have hailed because fatigue and loadings during handling and shipping of the filled containers. More specifically, containers filled with gas and oil additives and the like which are not carbonated) that have to be easily poured into openings on an automobile that are sometimes difficult to reach require a container with a pour opening adequate to handle the viscosity of the material and to direct the flow of same toward those difficult to reach places for filling. Enlarged pour openings defined by scoring tend to further weaken the easy opening end and magnify the problems of failure.
It is, therefore, an object of the invention to provide an easily opened retained tab end closure with a pour opening of sufficient shape and size to permit dispensing of noncarbonated material.
It is yet another object of the invention to provide a ring-pull retained tab end closure with a displaceable panel adequately fashioned to resist fatigue and static loadings.